This invention relates to a selector switch, and it relates in particular to such a switch which is useful for telephone dialing functions, e.g., in mobile radiotelephone applications.
Telephone dialing systems have traditionally required a user to see, or feel for, a spot at which to engage a finger to select a certain number for dialing. Then, in a dial pulse transmission system, the user operates a suitable mechanism to cause a telephone line circuit to be recurrently opened and closed according to a code in order to send the selected number. FIGS. 22-34 the A. E. Knowlton "Standard Handbook for Electrical Engineers," McGraw-Hill Book Company, New York, 1949, shows one example of a rotary dial mechanism.
It is well known in telephone systems to provide a visual display of dialed digits to enable a telephone station set user to verify the accuracy of a set of digits before initiating their transmission. U.S. Pat. Nos. 3,920,926 to Lenaerts et al., 2,921,142 to Tinus, and 2,433,398 to Richard are examples of such telephone station set arrangements. In each case, however, the user must be able by sight or touch to distinguish the respective digit selecting keys in order to input the desired information. In addition, Lenaerts et al. show an electronic system which allows the correction of a last-entered digit, and that feature tends to mitigate somewhat the likelihood of erroneous information transmission. Nevertheless, a user still must search out the respective dialing keys and the error correction key, if provided, by either visual or tactile means. In a Madden U.S. Pat. No. 2,635,230, a telephone dial is provided with a multi-apertured plate which is pivotally movable over a similarly configured plate bearing digit representations for achieving the transmission of signals representing selectable digits.
A Kennedy U.S. Pat. No. 2,922,994 is an example of a rotatable array of magnetic reed switches provided for sending electrical signals which are indicative of a rotatable shaft position. A McCreary U.S. Pat. No. 2,463,708 includes a rotary switch with a rotatable wiper for effecting circuit closure between a common wiper and a selectable one of plural fixed terminals.